The fourth of the Sargo class fleet submarines, SS-191 Sculpin was commissioned in 1939. During her shakedown cruise, she participated in the search for her sister boat, Squalus, which went down unexpectedly during a test dive on 23 May 1943 off Portsmouth. Sculpin located Squalus, and remained on station until U.S.S. Falcon arrived. Thirty-three men, including Squalus‘s commander, Lieutenant Oliver Naquin, were rescued. The 26 men in the after part of the boat drowned. Squalus was refloated, recommissioned Sailfish, and went on to run up an excellent wartime record.

Sculpin was in Cavite when World War II started, commanded by Lieutenant-Commander Lucius Chappell, departing on 8 December, along with Seawolf, to act as escorts for the seaplane tender Langley and the oiler Pecos. Having delivered her charges, Sculpin found a two-ship convoy on 10 January 1942, claiming hits on a 5,000-ton freighter.

On her second war patrol, Sculpin torpedoed the Japanese destroyer Suzukaze. The destroyer’s captain managed to save her by beaching his ship. On 6 February, Chappell fired two torpedoes at a light cruiser, claiming hits. Post war examination of Japanese records indicated no hits, and it is now presumed that the torpedoes, fitted with the notoriously unreliable—but then believed to be otherwise—Mark-6 magnetic influence exploder, prematured.

Eleven days later, Sculpin was detected by a Japanese destroyer, sustaining considerable damage in the subsequent depth charge attack. She was ordered to Australia for repairs.

Sculpin‘s third war patrol, out of Fremantle, was plagued by torpedo problems, and ended with no results. On her fourth patrol she claimed hits on a 4,000-ton freighter, two 8,000-ton tankers, and a 7,000-ton freighter. She was credited with the latter, but JANAC was unable to confirm the sinking from Japanese records after the war.

On her fifth war patrol, Sculpin was credited with 3 ships for 24,100 tons (reduced to 2 ships and 6,652 tons by JANAC). Her sixth patrol, now operating from Brisbane, produced no results. She then proceeded to Pearl Harbor, and from there returned to Mare Island for refit and modifications.

Following her refit, she returned to Pearl Harbor, departing from there for her seventh war patrol, in Empire waters, on 24 May 1943. Chappell claimed several hits, but none were credited.

One freighter was claimed on Sculpin‘s eighth war patrol, for 4,500 tons, later reduced by JANAC to 3,183 tons. This was Chappell’s last patrol in Sculpin, and she returned to Pearl Harbor for refit.

Commander Fred Connawway assumed command for Sculpin‘s ninth war patrol. Sculpin was working with Searaven on a mission to intercept Japanese vessels operating from Truk during the Gilbert Islands campaign. The intent was to also have Apogon and Spearfish join up with Sculpin and Searaven, and Sculpin was carrying Captain John Cromwell, who would act as wolf pack commander.

In retrospect, Cromwell probably should not have been allowed to go on the mission. He was an expert on “Ultra,” the code breaking system that was feeding American forces decrypts of Japanese operational orders, as well one of the senior planners of “Operation Galvanic” (the Gilberts campaign). This knowledge was to have unexpected consequences before the end of the patrol.

On the night of 18 November 1943, Sculpin made radar contact with a large convoy, following until morning, when she moved in to attack. Alert Japanese lookouts spotted her periscope, and the escorts immediately turned to attack. Sculpin was subject to two depth charge attacks, the second keeping her under for hours repairing damage. What was not realized until too late was that the depth gauge was also damaged.

When Connaway decided to go to periscope depth, the diving officer failed to realize that the depth gauge wasn’t moving, and instead of levelling off at 62 feet, Sculpin heaved herself to the surface with the depth gauge still reading 125 feet. She was spotted by the destroyer Yamagumo, which opened fire at once.

Yamagumo‘s first salvo hit Sculpin‘s bridge, killing Connaway, along with his executive and gunnery officers. With the senior officers dead, Lieutenant G.E. Brown, Jr. assumed command, ordering the crew to abandon and the boat to be scuttled. Cromwell decided to go down with Sculpin, fearing that he could be forced to reveal what he knew about “Ultra” and “Galvanic.” Ensign Fiedler, the diving officer who had failed to notice the defective depth gauge and presumably felt responsible for what had happened, also chose to go down with the boat.

The 41 survivors were split into two groups, and put aboard the aircraft carriers Chuyo and Unyo for transport to Japan. In an ironic twist, Chuyo was torpedoed and sunk by Sailfish—the raised and renamed Squalus—killing all but one of the 21 Sculpin survivors aboard.

Twenty-one survivors were liberated at the end of the war. Their testimony resulted in the posthumous award of the Medal of Honor to Captain Cromwell.